The present invention relates to an internal combustion fastener driving tool including a handle system that is coupled to and supports a drive system, a magazine, and a nose piece. The fastener driving system is operable through an internal combustion driven piston. The drive system includes a driver body which includes a piston housing in which a piston is slideably housed. A driving member is coupled to the piston. A combustion chamber is defined by the driver body, piston housing, and piston. The piston and driving member are axially arranged and configured within the piston housing to drive a fastener upon combustion of a metered amount of gaseous fuel in the combustion chamber.
A preferred fastener driving tool includes an accelerator plate. The accelerator plate is arranged and configured to divide the combustion chamber into a primary region and a secondary region. U.S. Pat. Nos. 4,365,471 and 4,510,748 describe a control wall and U.S. Pat. No. 4,712,379 describes a detonation plate, each of which provides certain structural and functional features of the accelerator plate. In addition, the accelerator plate has one or more features not found in the previously described control wall or detonation plate. Such features can include a plurality of inner orifices, a slot in the accelerator plate, a fuel metering tube, and an electrode. The inner orifices can provide improved combustion. The slot can house a radially oriented fuel metering tube, or a fuel metering tube can be an integral part of a preferred accelerator plate. An electrode incorporated into a preferred accelerator plate forms part of an ignition circuit.